The increasing reliance on communication networks to transmit more complex data, such as voice and video traffic, is causing a very high demand for bandwidth. To resolve this demand for bandwidth, communication networks are relying more upon optical fibers to transmit this complex data. Conventional communication architectures that employ coaxial cables are slowly being replaced with communication networks that comprise only fiber optic cables. One advantage that optical fibers have over coaxial cables is that a much greater amount of information can be carried on an optical fiber.
While carrying a greater amount of information is a tremendous advantage for optical fibers, this advantage does come with a price: sophisticated optical network architectures. One problem faced by many conventional optical network architectures is servicing subscribers that have various degrees or levels of demand for bandwidth. For example, in a conventional optical network architecture, if a home or personal use based subscriber is located adjacent to a business subscriber who has a greater need for bandwidth, conventional optical network architectures will provide the home subscriber with and business subscriber with different fiber optic cables. In other words, each subscriber in this scenario will be provided with its own separate fiber optic cable.
Such conventional optical network architectures using separate fiber optic cables for each customer because of bandwidth concerns adds to the complexity as well as the cost of such a system since separate hardware and software components are usually required to service two different fiber optic cables.
Unrelated to the multiple service/multiple bandwidth problems faced by many conventional optical network architectures, another problem faced by optical network architectures is the attenuation of video service signals. Specifically, when analog video optical signals are converted to the electrical domain for propagation over a coaxial cable, the higher frequencies of the video service signal typically loose signal strength faster than lower frequencies as the signals are propagated thorough the cable.
In order to compensate for this phenomenon, conventional optical network architectures sometimes place a tilt network at fiber optic nodes and RF amplifiers in their plant. Alternatively, some conventional optical network architectures increase the magnitude of their video signal strength at the head-end in order to overcompensate for this attenuation of high frequencies for the video service signal over the coaxial cables proximate to the subscribers. Placing a tilt network at the head-end can cause problems for individual subscribers such as personal or home use subscribers, since coaxial cables interfacing with an optical network typically have a relatively short length.
Another problem faced by conventional optical network architectures is servicing conventional set top terminals that require a return RF path to the head-end. A conventional RF return path typically comprises two-way RF distribution amplifiers with coaxial cables and two-way fiber optic nodes being used to interface with fiber optic cables. A pair of fiber optic strands can be used to carry the radio frequency signals between the head-end and node in an analog optical format. Each optical cable of the pair of fiber optic strands carries analog RF signals: one carries analog RF signals in the downstream direction (toward the subscriber) while the other fiber optic cable carries analog RF signals in the reverse or upstream direction (from the subscriber). In a more recent embodiment, the upstream spectrum (typically 5-42 MHz in North America) is digitized at the node. The digital signals are transmitted to the headend, where they are converted back to the analog RF spectrum of 5-42 MHz. This process typically uses high data rates (at least 1.25 Gb/s) and a fiber or wavelength dedicated to return traffic from one or two nodes.
Conventional optical network architectures typically do not comprise a return RF path from the subscriber to the data service hub because most of the return paths comprise only fiber optic cables that propagate digital data signals as opposed to analog RF signals. In conventional fiber-to-the-home (FTTH) and fiber-to-the-curb (FTTC) systems, a downstream RF path is usually provided because it is needed for the delivery of television programs that use conventional broadcast signals. This downstream RF path can support RF modulated analog and digital signals as well as RF modulated control signals for any set top terminals that may be used by the subscriber. However, as noted above, conventional FTTH systems do not provide for any capability of supporting a return RF path for RF analog signals generated by a legacy set top terminal.
Accordingly, in light of the problems identified above, there is a need in the art for a method and system for communicating optical signals to multiple subscribers having various bandwidth demands on a single optical waveguide. In other words, there is a need in the art for an optical network architecture that can service multiple subscribers along the same optical waveguide irrespective of the demand for bandwidth imposed by each subscriber of the network. Another need exists in the art for an optical network architecture that provides a central service disconnection point for a plurality of subscribers in a centralized location.
There is a further need in the art for positioning tilt networks in a centralized location outside a data service hub when servicing multiple subscribers of an optical network. A further need exists in the art for a method and system that provides a return path for RF signals that are generated by legacy video service terminals. A further need exists in the art for a method and system for communicating optical signals between a data service provider and subscriber that preserves the functioning of legacy set top converters using RF to communicate upstream to the headend.
Another need exists in the art for an optical network system that lends itself to efficient upgrading that can be performed entirely on the network side. In other words, there is a need in the art for an optical network system that allows upgrade to hardware to take place and locations between and within a data service hub and an active signal source disposed between the data service hub and a subscriber.
An additional need exists in the art for an optical network architecture that can take advantage of relatively inexpensive hardware components that typically service shorter distances than their expensive counterparts that service optical signals over large distances. There is a further need in the art for a system and method that can allocate additional or reduced bandwidth based upon the demand of one or more subscribers on an optical network.